Mexicans make up 60% of the nation's more than 50 million Hispanics, a new report finds. / Eric Gay, AP

by Haya El Nasser, @hayaelna, USA TODAY

by Haya El Nasser, @hayaelna, USA TODAY

New research shows that the segregation of Hispanics from whites in communities across the USA has declined significantly for every Hispanic group except the largest: Mexicans.

Mexicans make up 60% of the nation's more than 50 million Hispanics and are so dominant they drown out distinct characteristics of non-Mexicans, according to a report out Wednesday from the US2010 project, which researches changes in American society.

Segregation is one measure of how well immigrants are assimilating into U.S. society and is part of the conversation in the debate over immigration. For decades, Hispanic segregation was not declining.

"We thought Hispanic segregation stayed the same because we couldn't see the rest of the picture," says Brown University sociologist John Logan, director of US2010 and co-author of the report. "This seeming stability masks important differences, because every group except Mexicans has become less segregated since 1990."

Mexicans are a massive force in California and the Southwest, where predominantly Mexican communities were established generations ago and continue to attract more Mexicans. Large concentrations of Mexicans lead to more segregation, and their more recent dispersal to other parts of the U.S. hasn't been enough to move the needle.

"You have entire communities that are almost entirely Mexican in the Rio Grande Valley, and it's not going to change soon," says Arturo Vargas, executive director of the National Association of Latino and Elected Officials.

Vargas notes that Mexicans have a lower rate of becoming U.S. citizens than other immigrants. Just over a third of the 5.4 million legal Mexican immigrants eligible for citizenship were citizens in 2011 - about half the rate of naturalization among eligible legal immigrants from all other countries, according to Pew Research.

"That for us is a real concern," Vargas says. "It mutes our voice and limits the political voice of the community in American society."

The sheer size of the Mexican population is slowing the process of integration, says Roberto Suro, director of the Tomás Rivera Policy Institute at the University of Southern California.

Newer immigrants such as Dominicans and Central Americans still live in highly-segregated neighborhoods - even more segregated than Mexicans - but that pattern has declined steadily for 20 years.

"Dominicans went from really intense segregation in 1990 and have moved quite a bit," Suro says. "That's pretty substantial."

The research highlights the difficulty in reaching out to Hispanics as one, homogeneous group - an issue that influences national politics.

"Marco Rubio (Republican senator from Florida) is considered to be a great prospect because he's Cuban and can appeal to Hispanics," Logan says. "Cubans are highly concentrated in Florida and they're not a big group and very distinct from other Hispanics because they're higher-income and not recent immigrants. If you need help with Hispanics, somebody who appeals to Cubans is not necessarily what you're looking for."

The report shows:

Hispanics live in neighborhoods that have poorer and less educated residents than the neighborhoods non-Hispanic whites live in.

Mexicans are the least educated among more established Hispanic groups (average 10.5 years) and have relatively low incomes and high poverty. Most educated: South Americans and Panamanians.

Cubans, Puerto Ricans and some South Americans (Venezuelans, Argentinians) earn more on average than other Hispanics.

Dominicans and Central Americans generally earn less and have higher poverty rates.

"Hispanic isn't a single thing," Logan says. ... "They're not blending in as one Hispanic."